Intel 8086-1 Data Sheet Revision Review, reg 1 1, Bit w e Segment 000 001 010 011 100 101 110 111

8086

Table 2. Instruction Set Summary (Continued)

Mnemonic and	Instruction Code
Description

	7 6 5 4 3 2 1 0	7 6 5 4 3 2 1 0
PROCESSOR CONTROL
CLC e Clear Carry
	1 1 1 1 1 0 0 0
CMC e Complement Carry
	1 1 1 1 0 1 0 1
STC e Set Carry
	1 1 1 1 1 0 0 1
CLD e Clear Direction
	1 1 1 1 1 1 0 0
STD e Set Direction
	1 1 1 1 1 1 0 1
CLI e Clear Interrupt	1 1 1 1 1 0 1 0
STI e Set Interrupt
	1 1 1 1 1 0 1 1
HLT e Halt
	1 1 1 1 0 1 0 0
WAIT e Wait
	1 0 0 1 1 0 1 1
ESC e Escape (to External Device)
	1 1 0 1 1 x x x	mod x x x r/m
LOCK e Bus Lock Prefix
	1 1 1 1 0 0 0 0

NOTES:

AL e 8-bit accumulator AX e 16-bit accumulator CX e Count register DS e Data segment ES e Extra segment

Above/below refers to unsigned value Greater e more positive;

Less e less positive (more negative) signed values if d e 1 then ‘‘to’’ reg; if d e 0 then ‘‘from’’ reg

if w e 1 then word instruction; if w e 0 then byte instruc- tion

if mod e 11 then r/m is treated as a REG field

if mod e 00 then DISP e 0*, disp-low and disp-high are absent

if mod e 01 then DISP e disp-low sign-extended to 16 bits, disp-high is absent

if mod e 10 then DISP e disp-high; disp-low if r/m e 000 then EA e (BX) a (SI) a DISP if r/m e 001 then EA e (BX) a (DI) a DISP if r/m e 010 then EA e (BP) a (SI) a DISP if r/m e 011 then EA e (BP) a (DI) a DISP if r/m e 100 then EA e (SI) a DISP

if r/m e 101 then EA e (DI) a DISP if r/m e 110 then EA e (BP) a DISP* if r/m e 111 then EA e (BX) a DISP

DISP follows 2nd byte of instruction (before data if re- quired)

*except if mod e 00 and r/m e 110 then EA e disp-high; disp-low.

Mnemonics ' Intel, 1978

if s w e 01 then 16 bits of immediate data form the oper- and

if s w e 11 then an immediate data byte is sign extended to form the 16-bit operand

if v e 0 then ‘‘count’’ e 1; if v e 1 then ‘‘count’’ in (CL) x e don’t care

z is used for string primitives for comparison with ZF FLAG SEGMENT OVERRIDE PREFIX

0 0 1 reg 1 1 0

REG is assigned according to the following table:

16-Bit (w e 1)		8-Bit (w e 0)		Segment
000	AX	000	AL	00	ES
001	CX	001	CL	01	CS
010	DX	010	DL	10	SS
011	BX	011	BL	11	DS
100	SP	100	AH
101	BP	101	CH
110	SI	110	DH
111	DI	111	BH

Instructions which reference the flag register file as a 16-bit object use the symbol FLAGS to represent the file:

FLAGS e X:X:X:X:(OF):(DF):(IF):(TF):(SF):(ZF):X:(AF):X:(PF):X:(CF)

DATA SHEET REVISION REVIEW

The following list represents key differences between this and the -004 data sheet. Please review this summa- ry carefully.

1.The Intel 8086 implementation technology (HMOS) has been changed to (HMOS-III).

2.Delete all ‘‘changes from 1985 Handbook Specification’’ sentences.

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